Synthesis of multiphase Au/Cd0.6Zn0.4S/ZnS photocatalysts for improved photocatalytic performance

• Published in: International journal of hydrogen energy Vol. 44; no. 42; pp. 23589 - 23599
• Main Authors: Kozlova, Ekaterina A., Gribov, Evgenii N., Kurenkova, Anna Yu, Cherepanova, Svetlana V., Gerasimov, Evgeny Yu, Kozlov, Denis V.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 03-09-2019
• Subjects: Cd1-xZnxS; Photocatalytic hydrogen production; Photoelectrochemical properties; Visible light; Visible light; Photocatalytic hydrogen production; Cd1-xZnxS; Photoelectrochemical properties
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2019.07.081

Novel composite photocatalysts consisting of a cadmium and zinc sulfide solid solution (Cd0.6Zn0.4S) and zinc sulfide (ZnS) nanoparticles were successfully prepared by a simple hydrothermal treatment of suspended Cd0.3Zn0.7S at 120 °C. The as-obtained materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and UV-VIS diffuse reflection spectroscopy. The obtained photocatalysts were tested in the photocatalytic evolution of hydrogen from a Na2S/Na2SO3 aqueous solution under visible light irradiation (λ = 450 nm). It is shown that the hydrothermal treatment of Cd0.3Zn0.7S at 120 °C increases the activity by a factor of 7.5 due to the phase transformations of the solid solution with the formation of the multiphase Cd0.6Zn0.4S/ZnS sample. The deposition of gold on the surface of Cd0.6Zn0.4S/ZnS leads to a further increase in activity: the achieved photocatalytic activity and quantum efficiency (450 nm) for 1%Au/Cd0.6Zn0.4S/ZnS are 17.4 mmol g−1 h−1 and 42.6%, respectively. This excellent performance is found to be attributable to the transformation of Cd1-xZnxS from the cubic to the hexagonal phase during the hydrothermal treatment. Additionally, photoelectrodes based on Cd0.6Zn0.4S/ZnS and FTO were synthesized and tested in a two-electrode cell. A high value of the photocurrent equal to 0.5 mA/cm2 is achieved for the Cd0.6Zn0.4S/ZnS/FTO electrode. An investigation by means of impedance spectroscopy reveals the longer lifetime of photogenerated charge carriers in the Cd0.6Zn0.4S/ZnS/FTO photoelectrode if to compare with Cd0.3Zn0.7S/FTO system.
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•Au/Cd0.6Zn0.4S/ZnS photocatalysts were prepared via simple hydrothermal synthesis.•The highest value of the photocatalytic activity was 17.4 mmol H2 per hour per gram.•The highest apparent quantum efficiency was 42.6% (450 nm).•Photocurrent 0.5 mA/cm2 was achieved for the Cd0.6Zn0.4S/ZnS/FTO electrode.